NHA Phlebotomy Certification Practice Exam

Which type of tube should be used when collecting for a chemistry test that requires serum?

1. EDTA tube

2. SST tube

3. Plain red top tube

4. Blue top tube

The correct answer is: SST tube

The appropriate choice for collecting a sample for a chemistry test that requires serum is the SST tube. SST stands for Serum Separator Tube, which contains a gel that facilitates the separation of serum from the cellular components of the blood after the sample has been centrifuged. This is essential for many chemistry tests, as serum is the liquid portion that remains after blood has clotted and the cells have been removed. When a patient’s blood is drawn into the SST tube, it allows for clotting to occur, after which centrifugation helps separate the serum from the blood cells. This particular tube is often preferred in clinical settings because it allows for easier handling and processing, ensuring that the serum can be obtained quickly and efficiently without the need for additional steps. Additionally, while other tubes like the EDTA tube are used for tests requiring whole blood or plasma, they contain additives that are not appropriate for serum tests. The plain red top tube could potentially be used for serum, but the SST tube is designed specifically for serum collection and is more effective in yielding a clear serum sample, making it the preferred choice. The blue top tube is primarily used for coagulation studies and is also not suitable for obtaining serum.